*{
    margin: 0;
    padding: 0;
}
a{
    text-decoration: none;
}
ul{
    list-style-type: none;
}
.clearfix::before,.clearfix::after{
    display: block;
    content: '';
    clear: both;
}
.left{
    float: left;
}
.right{
    float: right;
}
.relative{
    position: relative;
}
.absolute{
    position: absolute;
}
.width{
    width: 1200px;
    margin: 0 auto;
}
/* 头部 */
.head{
    width: 100%;
    box-shadow: 0 5px 3px #808080;
}
/* 头部上半部分 */
.head_top{
    height: 108px;
}
.search_nav{
    border: 1px solid #f2f2f2;
    border-radius: 10px;
    margin-right: 150px;
    margin-top: 36px;
    width: 490px;
}
.search_nav input{
    width: 350px;
    height: 40px; 
    border: none;
    border-right: 1px solid #f2f2f2;   
    outline: none;
    margin-left: 7px;
}
.search_nav button{
    width: 120px;
    height: 40px;
    background-color: #fff;
    text-align: center;
    outline: none;
    border: none; 
    margin-left: -3px;   
}
/* 头部导航 */
.head_dw{
    padding: 10px 0;
    z-index: 10;
    background-color: #fff;
}
.head_dw .login{
    display: none;
}
.head_dw li{
    width: 80px;
    height: 40px;
    line-height: 40px;
    float: left;
    text-align: center;
}
.head_dw li:hover{
    border-bottom: 2px solid rgb(19, 59, 240);
}
.head_dw li a{
    color: #000;
    font-weight: bold;
    font-size: 16px;
}
.head_dw li a:hover{
    color: rgb(19, 59, 240);
}
.head_dw .mar{
    margin-top: 0px;
    display: none;
}
.active{
    border-bottom: 2px solid rgb(19, 59, 240);
}
.head_dw .active a{
    color: rgb(19, 59, 240);
}
/* 返回顶部 */
.returnTop{
    width: 65px;
    height: 65px;
    background-color: rgb(58, 62, 66);
    position: fixed;
    bottom: 20px;
    right: 50px;
    border-radius: 50%;
    cursor: pointer;
    display: none;
}
.returnTop img{
    width: 65px;
}